The book of Joshua is very appropriately named after its principal character
who dominates the scene throughout the entire book.

Joshua had been trained for his position as the leader of Israel as

an assistant to Moses. In Exodus 17:8-16 he had led the Israelites in victory
over the Amalekites. He was one of twelve spies sent to spy out the land of
Canaan in Numbers 13 and 14, and he was one of the two who advised an
immediate invasion of the land, asserting that by faith in God they would
conquer the land.

Although the liberal critics continue their JEDP Documentary Hypothesis
through Joshua, historical tradition has ascribed the book to Joshua, the son
of Nun. In reality, the book is anonymous. However, the book was obviously
written by an eyewitness; at least parts of the book are written by Joshua
himself (cf. 24:26); and archaic names were still in use in the book of Joshua,
some of which were changed shortly afterwards, suggesting that the narrative
was written very early.

It is reasonable, therefore, to conclude that Joshua wrote nearly all of the
book himself although some supplementary material such as the account of
Joshua's death may have been written by someone else, such as Eleazar or
Joshua's son, Phineas.

The book of Joshua illustrates the principle that the child of God will be in
conflict with evil powers and with Satan himself if he earnestly undertakes to
possess all that God has promised to him on this earth. It also illustrates the
victory able to be achieved when God's work is done in God's way.

The following outline is taken from Gleason L. Archer, A Survey of Old
Testament Introduction, p. 251-252: